1. Field of the Invention
The present invention relates to a module with a built-in component, wherein a cavity is disposed on the bottom surface side of a ceramic multilayer substrate, a circuit component is stored therein and, thereafter, resin molding is performed, and the present invention also relates to a method for manufacturing such a module.
2. Description of the Related Art
Various high-frequency modules, e.g., chip antennas, delay lines, high-frequency combination switch modules, and receiving devices, are incorporated in information communication apparatuses, e.g., portable terminals. These high-frequency modules are used while being mounted on mounting substrates, e.g., printed wiring boards. In structures of these high-frequency modules, circuit elements are mounted on multilayer substrates.
In recent years, electronic apparatuses, e.g., information communication apparatuses, have been miniaturized, and demands for miniaturization of high-frequency modules have also become intensified. However, if the area of a multilayer substrate is decreased, a problem occurs in that all of the circuit elements required for the module cannot be incorporated.
Consequently, in many cases, a cavity is disposed in a ceramic multilayer substrate, and a circuit component is incorporated in the inside of the cavity.
Japanese Unexamined Patent Application Publication No. 2000-77942 (Patent Document 1) discloses a surface-mount quartz oscillator in which a quartz resonator is incorporated on a ceramic multilayer substrate and, in addition, a cavity is disposed in the bottom surface of the ceramic multilayer substrate, an IC chip is stored in the cavity, and resin molding is performed.
Where a cavity is disposed in a bottom surface (mounting surface) of a ceramic multilayer substrate, as described above, external terminal electrodes are provided on a frame-shaped portion surrounding the cavity of the mounting surface of the ceramic multilayer substrate.
FIG. 9A is a diagram of such a ceramic multilayer substrate, viewed from a back surface direction. In the structure, a cavity 51 is disposed in a bottom surface of the ceramic multilayer substrate 50, and a mold resin 52 is molded to the cavity 51. External terminal electrodes 54 are disposed on a frame-shaped portion 53 surrounding the cavity 51.
However, as the miniaturization of the ceramic multilayer substrate advances, the width of the frame-shaped portion 53 must be decreased, as shown in FIG. 9B. This is because the number and the size of circuit components cannot be changed from the viewpoint of the circuit design and, therefore, the area of the cavity 51 cannot be decreased. Consequently, the area of the external terminal electrodes 54 cannot be adequately provided, and poor connections tend to occur when the incorporation on a mounting substrate, e.g., a motherboard, is performed. Even when the connection is performed normally, since the connection area is small, the connection portion tends to be peeled due to an impact from the outside and connection reliability problems occur.
On the other hand, it is also considered that the external terminal electrodes 54 are disposed on the mold resin 52 filled in the cavity 51. However, since the mold resin 52 is disposed by pouring a liquid resin and, thereafter, curing the resin, the surface may have a concave shape due to curing shrinkage, or the resin may swell upward. Therefore, it is difficult to form a flat surface. Consequently, the surface is not suitable for the formation of the external terminal electrodes 54.